The present invention generally relates to powder cosmetic compositions having enhanced tactile and wear properties. More particularly, the present invention relates to the preparation of loose and/or compacted powder formulations containing chitosan which increase the bulk density of particulate powders in a manner which increases the surface area covered by the powder when it is applied onto a substrate and, when used in powder cosmetic compositions, imparts improved feel properties onto human skin.
It is known that some cosmetic compositions such as blushes, eye shadows, face powders or foundations are provided in the form of compacted or cast powders. These are anhydrous compositions commonly referred to as “compact powders”. They mainly consist of a mixture of coloured or non-coloured powders and a fatty binder, such as an oil or a mixture of oil and wax, which are shaped by compression or by casting into a container serving as a mould. These powders are generally used by removing a small quantity of powder and then applying it to the skin by means of an applicator such as a sponge, powder puff or brush.
The preparation of binding agents in such compact powders poses various problems. The final product should be sufficiently homogeneous and compact in order to avoid the fragmentation caused especially by impact, while retaining good disintegration capacity. Moreover, the composition should have a smooth feel and should be easy to spread in a continuous manner. In addition, the binder should be compatible with pigments and specialists are familiar with the problems of degradation of certain pigments when conventional fatty binders are used.
Certain make-up compositions are also provided in the form of “loose powders”, wherein the particles are neither compacted nor dispersed in a fatty continuous phase, but retain on the contrary their individuality. Such loose powders often contain a fatty substance (oil) whose role is especially to increase the smoothness of application to promote the adherence of the powder to the skin, and to allow solubilization of some active ingredients. Some loose powders may contain relatively high quantities of oil without the particles having a tendency to agglomerate. Such is the case especially for powders containing particles in the form of hollow microspheres made from synthetic thermoplastic materials. However, the formulation of such loose powders poses the above-mentioned problem relating to the degradation of certain pigments in the presence of the fatty substances conventionally used.